In Korsmeyer-Peppas, what does 0.5 < n < 1 indicate?

• A. Fickian diffusion
• B. Case-II transport
• C. Anomalous transport
• D. Zero-order release

Answer: (C)

In the Korsmeyer-Peppas model, the release follows Mt/M∞ = k t^n, and the exponent n tells you which mechanism governs the drug release. When n falls between about 0.5 and 1, diffusion and the relaxation or swelling of the polymer both influence the process. This mixed control is called anomalous transport. It means the drug isn’t simply diffusing through a static polymer matrix, nor is the release governed purely by the polymer’s relaxation; instead, both factors contribute to the rate. For comparison, pure Fickian diffusion is around 0.5 (for a slab), and Case II (zero-order) release occurs when polymer relaxation dominates (n about 1). So 0.5 < n < 1 correctly indicates anomalous transport.